Multiple-cable lead with interrupted cable and crimp configuration

ABSTRACT

Example implantable cardiac electrotherapy leads are disclosed herein. In an example, a lead may include a plurality of cable conductors within an insulating jacket. A first one and a second one of the conductors include a proximal end at a proximal end of the jacket, the second conductor extends to at least the distal end of the jacket, and the first conductor includes a distal end at an intermediate location between the proximal end and the distal end of the jacket. The lead may also include a crimp connector connected to the first one of the cable conductors at the intermediate location, as well as a conductive element that may be connected to the crimp connector. A number of conductors along the proximal portion of the jacket may be greater than a number of conductors along at least a segment of the distal portion of the jacket.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. patent application Ser. No. 14/691,063, filedApr. 20, 2015.

FIELD OF THE INVENTION

The present invention relates to medical apparatus and methods ofmanufacturing such apparatus. More specifically, the present inventionrelates to implantable cardiac electrotherapy leads and methods ofmanufacturing such leads.

BACKGROUND OF THE INVENTION

Current implantable cardiac electrotherapy leads (e.g., cardiacresynchronization therapy (CRT) leads, bradycardia therapy leads, andtachycardia therapy leads) typically include multiple cable conductors.Each of the cable conductors may be electrically connected to anelectrode, shock coil, or other conductive element at some locationalong the lead to allow an electrical circuit to be formed inconjunction with the cardiac electrical system of a patient by way of alead coupled to a pacemaker, defibrillator, or other cardiac therapydevice.

While ongoing development of implantable cardiac electrotherapy leadshas resulted in at least some newer leads which have a helically woundlead body providing improved reliability, especially with respect toreduced cable fatigue, fractures, and abrasion, other potential concernsremain, such as electrical isolation between the cable conductors andoverall stiffness of the lead. More specifically, lack of electricalisolation between cable conductors may render the cardiac therapy deviceinoperative. In at least some cases, the possibility of unintendedelectrical coupling between cable conductors may be particularlypronounced at a distal end of the lead opposite the cardiac therapydevice.

Further, excessive stiffness of the lead may result in reducedflexibility for those applications in which the lead may benefit fromflexibility so that the attached conductive elements may reach allintended destinations in the body. Oppositely, some applications mayrequire more strength and, consequently, less flexibility so that, forexample, the lead or a conductive element attached thereto may betorqued or pushed to properly position the lead.

With the above aspects in mind, as well as others not explicitlydiscussed herein, various embodiments of an implantable cardiacelectrotherapy lead, as well as embodiments for manufacturing suchleads, are disclosed herein.

SUMMARY

In one embodiment, an implantable cardiac electrotherapy lead mayinclude a plurality of cable conductors within at least one lumen of aninsulating jacket. A first one and a second one of the cable conductorsmay include a proximal end at a proximal end of the jacket, the secondone of the cable conductors may extend to at least the distal end of thejacket, and the first one of the cable conductors may include a distalend at an intermediate location between the proximal end and the distalend of the jacket. The lead may also include a crimp connector connectedto the first one of the cable conductors at the intermediate location,as well as a conductive element that is connected to the crimpconnector. A number of cable conductors along the proximal portion ofthe jacket are greater than a number of cable conductors along at leasta segment of the distal portion of the jacket.

In another embodiment, a method of manufacturing an implantable cardiacelectrotherapy lead may include receiving a length of lead stock, inwhich the stock comprises a plurality of cable conductors and aninsulating jacket defining at least one lumen within which the cableconductors are located. An opening may be formed in the jacket at anintermediate location between a proximal end and a distal end of thelength of lead stock. At least one of the cable conductors may beinterrupted at the opening in the jacket to form a proximal portion anda distal portion of the at least one cable conductor. A crimp connectormay be connected to the proximal portion at the opening, and aconductive element may be connected to the crimp connector. At least asegment of the distal portion of the at least one cable conductor may beremoved.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which depicts and describesillustrative embodiments of the invention. As will be realized, theinvention is capable of modifications in various aspects, all withoutdeparting from the scope of the present invention. Accordingly, thedrawings and detailed description are to be regarded as illustrative innature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an isometric view of a longitudinal segment of an examplehelically wound lead body including two cable conductors, in which anouter jacket of the lead body is largely hidden to reveal a helical coreassembly of the lead body.

FIG. 1B is a longitudinal side view of the example lead body of FIG. 1Ain which the outer jacket is depicted in phantom lines to reveal thehelical core assembly.

FIG. 1C is a transverse cross-sectional view of the example lead body ofFIG. 1A as taken along section line 1C-1C in FIG. 1B.

FIG. 2 is a transverse cross-sectional view of an example lead bodyincluding four cable conductors.

FIG. 3 is a partial longitudinal side view of an example lead body withan opening in an outer jacket and a core jacket to access a cableconductor within.

FIG. 4 is a partial longitudinal side view of the example lead body ofFIG. 3 in which the cable conductor being accessed is interrupted.

FIG. 5 is a partial longitudinal side view of the example lead body ofFIG. 4 with a crimp connector attached to a proximal portion of theinterrupted cable conductor being accessed.

FIG. 6A is an enlarged side view of an example cylindrical crimpconnector for connecting a conductive element to the proximal portion ofthe interrupted cable conductor depicted in FIG. 5.

FIG. 6B is an enlarged end view of the example cylindrical crimpconnector of FIG. 6A.

FIG. 7A is an enlarged oblique view of an example crimp-through crimpconnector for connecting a conductive element to the proximal portion ofthe interrupted cable conductor depicted in FIG. 5.

FIG. 7B is an enlarged end view of the example crimp-through crimpconnector of FIG. 7A.

FIG. 7C is an enlarged top view of the example crimp-through crimpconnector of FIG. 7A.

FIG. 7D is an enlarged side view of the example crimp-through crimpconnector of FIG. 7A.

FIG. 8 is a partial longitudinal side view of the example lead body ofFIG. 5 with a second opening in the outer jacket and core jacket toaccess and remove a segment of a distal portion of the interrupted cableconductor.

FIG. 9 is partial longitudinal side view of an example lead of the leadbody of FIG. 8, to which several conductive elements have been connectedto the proximal portion of multiple interrupted cable conductors.

FIG. 10 is a flow diagram of an example method of manufacturing animplantable cardiac electrotherapy lead.

DETAILED DESCRIPTION

The following detailed description relates to implantable cardiacelectrotherapy leads. In one example, a lead may include a plurality ofcable conductors within at least one lumen of an insulating jacket. Afirst one and a second one of the cable conductors may include aproximal end at a proximal end of the jacket, the second one of thecable conductors may extend to at least a distal end of the jacket, andthe first one of the cable conductors may include a distal end at anintermediate location between the proximal end and the distal end of thejacket. The lead may also include a crimp connector connected to thefirst one of the cable conductors at the intermediate location, as wellas a conductive element that is connected to the crimp connector. Anumber of cable conductors along the proximal portion of the jacket maybe greater than a number of cable conductors along at least a segment ofthe distal portion of the jacket.

In some embodiments, as disclosed below, a method of manufacturing animplantable cardiac electrotherapy lead may include receiving a lengthof lead stock that includes a plurality of cable conductors and aninsulating jacket defining at least one lumen in which the cableconductors are located. An opening in the jacket may be formed at anintermediate location between a proximal end and a distal end of thelength of lead stock. At least one of the cable conductors may beinterrupted at the opening to form a proximal portion and a distalportion of the at least one cable conductor. A crimp connector may beconnected to the proximal portion of the at least one cable conductor atthe opening, and a conductive element may be connected to the crimpconnector. At least a segment of the distal portion of the at least onecable conductor may be removed from the at least one lumen.

As a result of at least some of the embodiments discussed in greaterdetail below, the interruption of the at least one cable conductor mayfacilitate greater electrical isolation between the at least one cableconductor and other cable conductors of the lead. This isolation may befurther enhanced by interrupting the distal portion of the at least onecable conductor at a second opening, or by removing the entirety of theat least one cable conductor from the lead. Other aspects and potentialadvantages of the embodiments disclosed herein are also presented below.

For a discussion regarding a lead body upon which embodiments disclosedherein may be based, reference is made to FIGS. 1A-1C. FIG. 1A is anisometric view of a longitudinal segment of an example lead body 100including two cable conductors 185 and 190, in which an outer jacket 105of the lead body 100 is largely hidden to reveal a helical core assembly110 of the lead body 100. FIG. 1B is a longitudinal side view of thelead body 100 of FIG. 5A in which the outer jacket 105 is depicted inphantom lines to reveal the helical core assembly 110. FIG. 1C is atransverse cross-sectional view of the lead body 100 as taken alongsection line 1C-1C in FIG. 1B.

As indicated in FIGS. 1A-1C, in one embodiment, the helical coreassembly 110 forms a central or core portion 110 of the lead body 100and is enclosed by the outer jacket 105, which forms an outercircumferential surface 115 of the lead body 100. The outer jacket 105may be formed of silicone rubber, silicone rubber-polyurethane-copolymer(SPC), polyurethane, or another material. As mentioned below, othertypes of lead bodies employable in the embodiments described herein maynot employ an outer jacket 105.

As illustrated in FIG. 1C, in one embodiment, the helical core assembly110 includes an inner liner 120, a pair of cable conductors 185, 190,and a core jacket 125. The inner liner 120 includes inner and outercircumferential surfaces 130, 135. The inner circumferential surface 130of the inner liner 120 may define a central lumen 140 of the lead body100 through which a guidewire and/or stylet may be extended during therevision and implantation of the resulting lead. In one embodiment, theinner liner 120 may be formed of a polymer material such as ethylenetetrafluoroethylene (ETFE), polytetrafluoroethylene (“PTFE”), and/oranother material.

As further indicated in FIG. 1C, in one embodiment, the two conductors85, 90 are located outside the inner liner 120 adjacent to the outercircumferential surface 135 of the inner liner 120. The two conductors85, 90 may be evenly radially spaced from each other about the outercircumferential surface 135 of the inner liner 120. The conductors 85,90 may have electrically conductive cores 185 a, 190 a, and each of thecable conductors 185, 190 may or may not have corresponding individualelectrical insulation jackets 185 b, 190 b. In examples in which thecable conductors 185, 190 have insulation jackets 185 b, 190 b, theinsulation jackets 185 b, 190 b may be formed of a polymer material suchas ETFE, PTFE, and/or another material. The electrically conductivecores 185 a, 190 a may be multi-wire or multi-filar cores or solidsingle wire cores.

As depicted in FIG. 1C, the helical core assembly 110 may have two cableconductors 185, 190 that are evenly radially spaced apart from eachother about the inner liner 120. However, in other embodiments, thecable conductors 185, 190 may have other arrangements. For example, thehelical core assembly 110 may include greater than two cable conductors185, 190, and the cable conductors 185, 190 may be routed in groups(e.g., pairs) of conductors such that the conductors are not radiallyspaced apart. More specifically, the coils of the helically routedconductors 185, 190 may actually contact each other despite having apitch that results in an overall length that is not substantiallygreater than a straight-routed conductor.

As can be understood from FIGS. 1A and 1B, the cable conductors 185, 190longitudinally extend along the outer circumferential surface 135 of theinner liner 120 in a helical wind about a central axis of the lead body100, such as that defined by the inner liner 120. In other examples,however, the conductors 185, 190 may extend directly along the length ofthe lead body 100 without any wind, helical or otherwise. In someembodiments, the pitch of the helically-routed cable conductors 185, 190is between approximately 0.05 inches and approximately 0.3 inches.

As shown in FIG. 1C, the core jacket 125 includes an inner surface 145and an outer surface 150. The core jacket 125 extends about the cableconductors 185, 190 and the inner liner 120, thereby enclosing the innerliner 120 and the conductors 185, 190 within the core jacket 125. Inother embodiments, a core jacket 125 may not be utilized.

As further illustrated in FIG. 1C, the core jacket 125 may fit snugglyabout the inner liner 120 and the cable conductors 185, 190 such thatthe inner surface 145 of the core jacket 125 extends along and generallyconforms to portions of the outer circumferential surface 135 of theinner liner 120 and the outer surfaces of the cable conductors 185, 190(e.g., the outer surfaces of the conductor insulation 185 b, 190 b,where present). In examples in which two cable conductors 185, 190 areemployed, the resulting transverse cross-section of the helical coreassembly 110 may have a first diameter D1, which is aligned with a firstaxis A extending through the center points of the cable conductors 185,190 and the central lumen 140, that is substantially larger than asecond diameter D2, which is aligned with a second axis B that isgenerally perpendicular to the first axis A. In one example, the firstdiameter D1 may be approximately 0.05 inches.

As shown in FIGS. 1A and 1B, as a result of the helical routing of thecable conductors 185, 190 about the inner liner 120 and the generalconforming of the core jacket 125, the outer surface 150 of the corejacket 125 may also be helical, thus defining two helically extendingtroughs 155 a, 155 b separated by two helically extending ridges 160 a,160 b. Where the helical core assembly 110 includes three, four, or morehelically-routed conductors, and the core jacket 125 generally conformsto the cable conductors 185, 190 and the inner liner 120, the outersurface 150 of the core jacket 125 may exhibit a corresponding number oftroughs and ridges.

As can be understood from FIGS. 1A-1C, the location and routing of eachhelically extending ridge 160 a, 160 b corresponds to and generallymatches the location and routing of a specific helically-routed cableconductor 185, 190. The location and routing of each helically extendingtrough 155 a, 155 b corresponds and generally matches the location of aspace centered between a pair of helically-routed cable conductors 185,190.

As indicated in FIG. 1C, in one embodiment, the helical core assembly110 is encased or imbedded in the material of the outer jacket 105 ofthe lead body 100, the outer circumferential surface 115 of the outerjacket 105 forming the outer circumferential surface 115 of the leadbody 100. As indicated in FIG. 1C, the outer jacket 105 may in-fillvoids between the lead body outer circumferential surface 115 and thecore jacket outer surface 150 in the vicinity of the troughs 155 a, 155b. The result may be a lead body 100 with an outer circumferentialsurface 115 having a generally circular shape in transversecross-section and generally uniform diameter along its length, despitethe helical core assembly 110 having a transverse cross-section that issemi-elliptical.

As mentioned above, the lead body 100 may include any number of cableconductors, including two conductors, three conductors, and so on. Forexample, FIG. 2, which is a transverse cross-sectional view similar toFIG. 1A, depicts a lead body 200 in which four cable conductors 185,186, 190, and 191 are helically wound about an inner liner 120 thatdefines a central lumen 140. Also similar to the lead body 100, a corejacket 125 may surround the four cable conductors 185, 186, 190, and 191and the inner liner 120. In addition, an outer jacket 105 may beemployed to cover substantially the core jacket 125, potentially torender a substantially circular cross-section for the lead body 200. Inother examples, an outer jacket 105 may not be utilized. As with thediameter D1 of the lead body 100 of FIG. 1C, the largest diameter of thelead body 200 may be approximately 0.05 inches.

Any of the example lead bodies 100, 200 described above, as well asothers, may be employed to produce implantable cardiac electrotherapyleads for monitoring, synchronization, and other cardiac electrotherapyuses. FIG. 3 is a partial longitudinal side view of an example lead body300 that is in the process of being modified to produce such a lead. Inone embodiment, the lead body 300 may be a length of pre-manufacturedlead stock that has been cut from a spool or other container of leadstock. More specifically, the lead body 300 may include multiple cableconductors, including a cable conductor 385 that has been selected for aconnection with a conductive element at a particular intermediatelocation between a proximal end 301 and a distal end 302 of the leadbody 300. In one example, the proximal end 301 is to be prepared forcoupling with a pacemaker, defibrillator, or other cardiac therapydevice, with one or more conductive elements to be located along thelead body 300 from the proximal end 301 to the distal end 302 andconnected to selected cable conductors of the lead body 300.

As shown, the lead body 300 may include four helically wound cableconductors, including the selected cable conductor 385, similar to thelead body 200 of FIG. 2, although other numbers and types of lead bodiesmay be employed in other examples. As shown, one or more of the cableconductors, including the selected cable conductor 385, may be coatedwith an individual insulating sleeve or material, as mentioned above.

In this example, a technician or other personnel, or a machineconfigured to perform the various operations described hereinautomatically, has formed an opening 308 in an outer jacket 305 and acore jacket (not explicitly shown in FIG. 3), such as by way of cuttingor other means to gain mechanical access to the selected cable conductor385 at a desired location for connection to the conductive element. Inother embodiments, the outer jacket 305 or the core jacket may not bepresent in the lead body 300. In other examples, the outer jacket 305and/or the core jacket may not extend long an entirety of the lead body300,

FIG. 4 is a partial longitudinal side view of the example lead body 300of FIG. 3 in which the selected cable conductor 385 accessed isinterrupted. In one example, a technician may cut the selected cableconductor 385 with cutters, pliers, or another tool to form a proximalportion 388 and a distal portion 389 of the selected cable conductor385. In one particular example, the technician may cut or interrupt theselected cable conductor 385 at a distal end 387 of the opening 308 toallow the portion of the selected cable conductor 385 that is exposedvia the opening 308 to remain accessible for attaching a crimp connectorthereto. As shown in FIG. 4, the accessible portion of the selectedcable conductor 385 may be temporarily extracted from the outer jacket305 and/or core jacket to facilitate access to an exposed distal end 395of the proximal portion 388 of the selected cable conductor 385 to allowthe placement of a crimp connector over the end 395.

In this example, by cutting or otherwise interrupting the selected cableconductor 385, as opposed to exposing the selected cable conductor 385for subsequent connection to a conductive element, such as an electrodeor shock coil, the proximal portion 388 and the distal portion 389 ofthe selected cable conductor 385 may be effectively isolatedelectrically. Such isolation may help prevent short circuits or otherunwanted electrical coupling between the proximal portion 388 of theselected cable conductor 385 and other cable conductors of the lead body300, such as what may occur as a result of a connector being attached atthe distal end 302 of the lead body 300, at which the various cableconductors terminate.

FIG. 5 is a partial longitudinal side view of the example lead body 300of FIG. 4 with a crimp connector 392 attached to the proximal portion388 of the interrupted cable conductor 385. In one example, the crimpconnector 392 is slid over the distal end 395 of the proximal portion388 of the selected cable conductor 385 such that the crimp connector392 radially surrounds the selected cable conductor 385. One particularexample crimp connector is illustrated in FIGS. 6A and 6B, while anotherexample crimp connector is depicted in FIGS. 7A-7D, although many othertypes of crimp connectors may be mechanically and electrically coupledto the selected cable conductor 385 in other embodiments. In yet furtherexamples, connectors other than crimp connectors may be employed.

FIG. 6A is an enlarged side view of an example cylindrical crimpconnector 600 for connecting a conductive element to the proximalportion 388 of the interrupted cable conductor 385 depicted in FIG. 5,and FIG. 6B is an enlarged end view of the example cylindrical crimpconnector 600 of FIG. 6A. Generally, the cylindrical crimp connector 600may be fabricated from a strong, deformable, and electrically conductivematerial as a cylinder with an exterior radial surface 602 and defininga longitudinal channel 606 via an interior radial surface 604 extendingalong a central longitudinal axis of the cylinder. Consequently, thecylindrical crimp connector 600 includes two end faces 608 at opposingends of the connector 600.

In one embodiment, the cylindrical crimp connector 600 may be a segmentof pre-drawn tubing. In one embodiment, the cylindrical crimp connector600 may be formed of a metal or alloy material (e.g., platinum-iridium,MP35N®, or stainless steel). In other embodiments, the cylindrical crimpconnector 600 may be formed via other manufacturing processes, such asmetal injection molding.

In a particular example, the cylindrical crimp connector 600 may have alength L6 of approximately 0.05 inches, an inner diameter ID6 ofapproximately 0.0165 inches, an outer diameter OD6 of approximately0.025 inches, and a thickness T6 of approximately 0.004 inches. However,many different sizes and dimensions for the cylindrical crimp connector600 may be utilized in other embodiments.

In examples in which the selected cable conductor 385 is covered with alayer or coating of insulation, the insulation may be stripped orotherwise removed from the selected cable conductor 385 prior to slidingthe cylindrical crimp connector 600 over the distal end 395 of theproximal portion 388 of the selected cable conductor 385. Thecylindrical crimp connector 600 may then be crimped using a crimpinganvil and die, or other crimping tool or machine, to create a secureconnection between the proximal portion 388 of the selected cableconductor 385 and the cylindrical crimp connector 600. Such crimpingmay, for example, deform the cylindrical crimp connector 600 to securelycapture the proximal portion 388 of the selected cable conductor 385,thus altering the shape of the channel 606 of the cylindrical crimpconnector 600 from a circular shape to a somewhat oval or othernoncircular appearance. Accordingly, the selected cable conductor 385may securely contact at least portions of the interior radial surface604 to create an electrical connection therebetween.

FIGS. 7A-7D depict various views of another type of crimp connector 392:a crimp-through crimp connector 700. More specifically, FIG. 7A is anenlarged oblique view of an example crimp-through crimp connector 700for connecting a conductive element to the proximal portion 388 of theinterrupted cable conductor 385 depicted in FIG. 5, FIG. 7B is anenlarged end view of the example crimp-through crimp connector 700 ofFIG. 7A, FIG. 7C is an enlarged top view of the example crimp-throughcrimp connector 700 of FIG. 7A, and FIG. 7D is an enlarged side view ofthe example crimp-through crimp connector 700 of FIG. 7A. Similar to thecylindrical crimp connector 600, the crimp-through crimp connector 700may be fabricated from a strong, deformable, and electrically conductivematerial taking the general shape of a cylinder with an exterior radialsurface 702 and defining a longitudinal channel 706 via an interiorradial surface 704 extending along a central longitudinal axis of thecylinder. Accordingly, the crimp-through crimp connector 700 includestwo end faces 708 at opposing ends of the connector 700.

As with the cylindrical crimp connector 600, the crimp-through crimpconnector 700, in one embodiment, may be a segment of pre-drawn tubing.In one embodiment, the crimp-through crimp connector 700 may be formedof a metal or alloy material (e.g., platinum-iridium, MP35N®, orstainless steel). In other embodiments, the crimp-through crimpconnector 700 may be formed via other manufacturing processes, such asmetal injection molding and so on.

In a particular example, the crimp-through crimp connector 700 may havea length L7 of approximately 0.04 inches, an inner diameter ID7 rangingapproximately from 0.012 inches to 0.014 inches, and a wall thickness T7ranging approximately from 0.004 inches to 0.005 inches. However, manydifferent sizes and dimensions for the crimp-through crimp connector 700other than those disclosed herein may be utilized in other embodiments.

Unlike the cylindrical crimp connector of FIGS. 6A and 6B, thecrimp-through crimp connector 700, when crimped onto the distal end 395of the proximal portion 388 of the selected cable conductor 385, may beconfigured to penetrate insulation that may be covering the selectedcable conductor 385, thus potentially eliminating a need to remove theinsulation from the area of interest of the selected cable conductor 385prior to placing and crimping the crimp-through crimp connector 700 ontothe selected cable conductor 385.

To provide such a feature, the crimp-through crimp connector 700 maydefine one or more splice openings 710 joining the interior radialsurface 704 and the exterior radial surface 702, and having one or morerelatively sharp edges 712 at the interior radial surface 704. In oneembodiment, each splice opening 710 may be formed by laser cutting,resulting in the sharp edges 712 where the interior radial surface 704intersects the splice opening 710.

The splice openings 710 may be any shape. As shown in FIGS. 7A and 7C,the splice openings 30 may be in the shape of a rectangular slot and maybe oriented transverse to the longitudinal axis of the crimp-throughcrimp connector 700. In the case of a slot-type splice opening 710, theslot may extend across the crimp-through crimp connector 700 and have alength substantially equal to the inner diameter ID7 42 associated withthe channel 706.

When the crimp-through crimp connector 700 is squeezed, pressed, orotherwise caused to crimp the proximal portion 388 of the selected cableconductor 385, the sharp edges 712 formed between each splice opening712 and the interior radial surface 704 may cause the insulation of theselected cable conductor to be severed to promote electrical contactbetween the crimp-through crimp connector 700 and the conductive core ofthe proximal portion 388 of the selected cable conductor 785. In theexample of FIGS. 7A-7D, this severing of the insulation may occur atboth of the two splice openings 710 depicted therein. Moreover, thiscrimping process may cause the proximal portion 388 of the selectedcable conductor 385 to be secured within the connector 700 due tofrictional resistance between the cable conductor 385 and the interiorradial surface 704, as well as to bearing-type resistance betweenbulging portions of the cable conductor 385 extending through the spliceopenings 710 toward the exterior radial surface 702.

In other embodiments, the splice openings 710 may not extend all the wayto the external radial surface 702 of the connector 700. In thisembodiment, the splice opening 710 may comprise a recess on the internalradial surface 704, allowing for similar severing and connectioncapabilities as those described above. Other variations of thecrimp-through crimp connector 700 are possible in other examples aswell.

FIG. 8 is a partial longitudinal side view of the example lead body 300of FIG. 5 with a second opening 309 in the outer jacket 305 and corejacket (not explicitly shown in FIG. 8) to access and remove a segment398 of the distal portion 302 of the interrupted cable conductor 385. Asshown, the second opening 309 may be large enough so that the distalportion 302 of the interrupted cable conductor 385 may be cut orotherwise interrupted at each end of second opening 309 to yield andsubsequently remove the segment 398 from the lead body 300. By cuttingor interrupting the distal portion 302 of the interrupted cableconductor 385 at the second opening 309, electrical isolation betweenthe proximal portion 388 of the selected cable conductor 385 and othercable conductors of the lead body 300 may be further enhanced.

The location of the second opening 309 along the distal portion 302 ofthe interrupted cable conductor 385 may be selected based on a desire toprovide slightly more flexibility in the lead body 300 at the secondopening 309. In one example, the second opening 309 may be a location atwhich a conductive element, such as an electrode or a shock coil, may beconnected to a cable conductor of the lead body 300 other than theinterrupted cable conductor 385.

In another example, a segment of the distal portion 302 of theinterrupted cable conductor 385 between the first opening 308 and thesecond opening 309 may be removed by pulling or sliding that segmentfrom the first opening 308 or the second opening 309. Similarly, thesegment of the distal portion 302 of the interrupted cable conductor 385between the second opening 309 and the distal end 302 of the lead body300 may be removed by pulling or sliding that segment from the secondopening 309 or the distal end 302 of the lead body 300.

In another embodiment, the entire distal portion 389 of the interruptedcable conductor 385 may be removed from the lead body 300. For example,assuming that friction between the distal portion 389 and the corejacket and/or outer jacket 305 of the lead body 300 is below somethreshold, the distal portion 389 may be pulled from the lead body 300at either the first opening 308 or the distal end 302 of the lead body300, thus completely removing the distal portion 389 from the lead body300. While this removal may further enhance electrical isolation betweenthe proximal portion 388 of the interrupted cable conductor 385 and theother cable conductors of the lead body 300, flexibility along theportion of the lead cable 300 corresponding with the removed distalportion 389 of the interrupted cable conductor 385 may be increased.This flexibility may be advantageous in several cardiac therapyapplications, such as, for example, CRT leads to be implanted in cardiacveins, as well as bradycardia and tachycardia therapy leads to beimplanted into the right ventricle of the heart. In other applications,however, the original strength of the lead body 300 may be preferredover lead flexibility. In such applications, the interrupting of thedistal portion 389 of the interrupted cable conductor 385, along withthe possible removal of a relatively short segment of the distal portion389, may be preferred over the complete removal of the distal portion389.

After removal of either the segment 398 or the entirety of the distalportion 389 of the interrupted cable conductor 385, the electricalisolation of the cable conductors within the lead body 300 may befurther improved by blocking potential fluid pathways between the cableconductors that may have been created by the removal of the segment 398or the entirety of the distal portion 389. In one embodiment, at least aportion of a lumen that previously carried either the segment 398 or theentirety of the distal portion 389 of the interrupted cable conductor385 may be filled with an electrically insulating material via the firstopening 308, the second opening 309, and/or the distal end 302 of thelead body 300, depending on the extent of the lumen to be filled. In oneexample, the insulating material may acquire a liquid state when heated,thus allowing the insulating material to enter the lumen by suction,pressure, and/or other means. After cooling, the insulating material maythen acquire a more solid state that retains substantial flexibility.

In another embodiment, the lead body 300 may be heated to reflow theouter jacket 305 and/or the core jacket, thus at least partially fillingthe portion of the lumen that previously carried either the segment 398or the entirety of the distal portion 389 of the interrupted cableconductor 385. As additional material is not added to the lead body 300in this embodiment, a high level of flexibility may be maintained in theportion of the lead body 300 corresponding to the removed segment 398 orentirety of the distal portion 389 of the interrupted cable conductor385.

While the above discussion focuses on the interruption and relatedoperations associated with a single selected cable conductor 385,similar operations may be performed on multiple cable conductors of thelead body 300. FIG. 9 is partial longitudinal side view of the examplelead body 300 of FIG. 8, to which several conductive elements have beenconnected to the proximal portion of multiple interrupted cableconductors, resulting in a completed cardiac lead 900. In this example,each of the four cable conductors of the lead body 300 may be coupled toa separate conductive element 902, 904, 906, and 908. More specifically,conductive elements 902, 904, and 906 may be ring electrodes, with eachring electrode 902, 904, and 906 being positioned along the lead body300 at a particular point between the proximal end 301 and the distalend 302 of the lead body 300 to be placed in contact with particularregions of the cardiac system of a patient. The conductive element 908may be an end electrode 908 with an active-fixation structure (e.g., acorkscrew or helix structure) or a passive-fixation structure (e.g., oneor more straight fins or tines) located at the distal end 302 of thelead body 300 to help physically anchor the lead body 300 to the cardiacsystem of the patient. Each of the electrodes 902, 904, 906, and 908 maybe connected with its corresponding connector 392 by way of laserwelding, resistance welding, swaging, crimping, bonding, or other means.In yet other examples, other types of conductive elements, such as shockcoils, may be employed for the lead 900.

In this example, each of the three ring electrodes 902, 904, and 906 aremechanically and electrically connected to a distal end 395 of aproximal portion 388 of a corresponding cable conductor that has beencut or otherwise interrupted to form a proximal portion 388 and a distalportion 389. Further, the distal portion 395 of each of the threecorresponding cable conductors has been removed from the lead body 300,and the lumens associated with the removed portions have been reflowedor filled with insulating material. In contrast, the cable conductorthat is mechanically and electrically connected to the end electrode 908at the distal end 302 of the lead body 300 is not interrupted, and thusextends from the proximal end 301 to the distal end 302 of the lead body300.

Consequently, the resulting lead 900 exhibits four different sections910, 912, 914, and 916 of differing flexibility based on the number ofcable conductors remaining in that section. More specifically, the firstsection 910 between the proximal end 301 of the lead body 300 and thefirst ring electrode 902 includes four cable conductors, and thusexhibits the lowest relative flexibility of the four sections. Thesecond section 912 between the first ring electrode 902 and the secondring electrode 904 includes three cable conductors, and is thusrelatively more flexible than the first section 910 due to the removalfrom the lead body 300 of the distal portion 389 of the cable conductorconnected to the first ring electrode 902. Similarly, the third section914 between the second ring electrode 904 and the third ring electrode906 includes two cable conductors, and is thus relatively more flexiblethan the second section 912 due to the removal from the lead body 300 ofthe distal portion 389 of the cable conductors connected to the firstring electrode 902 and the second ring electrode 904. Finally, thefourth section 916 between the third ring electrode 906 and the endelectrode 908 includes a single cable conductor to connect the endelectrode 908 to the proximal end 301 of the lead body 300, and is thusrelatively more flexible than the third section 914 due to the removalfrom the lead body 300 of the distal portion 389 of the cable conductorsconnected to the ring electrodes 902, 904, and 906.

In other embodiments, the distal portion 389 of one or more of the cableconductors, after interruption, may be left as is, or may be interruptedagain via one or more additional openings in the outer jacket 305 and/orcore jacket, instead of being completely removed, to retain some higherlevel of rigidity within one or more of the sections 912, 914, and 916of the resulting lead 900.

In the particular example of FIG. 9, as each electrode 902, 904, and 906of the lead 900 is associated with a single cable conductor, the lead900 may represent a unipolar lead, in which the return current path foreach of the cable conductors in provided by the human body back to thesource of the current (e.g., a pacemaker, defibrillator, or othercardiac therapy device) at the proximal end 301 of the lead body 300. Inother examples, one or more additional cable conductors may be employedin the lead body 300 for the return current path for one or more of theelectrodes 902, 904, 906, and 908, thus resulting in a bipolar lead. Inyet other embodiments, more than one cable conductor may be coupled witha particular electrode 902, 904, 906, and 908, with one or more of thosecable conductors being interrupted and subsequently processed, asdescribed above.

Based on the various embodiments of the lead body 300 described above,FIG. 10 is a flow diagram of an example method 1000 of manufacturing animplantable cardiac electrotherapy lead. In the method 1000, a length oflead stock may be received (operation 1002), such as from a spool orother container of stock. The lead stock may include multiple cableconductors, which may be helically wound, straight-routed, or otherwisearranged within the lead stock, as discussed above. The lead stock mayalso include an inner liner 120 with associated central lumen 140, acore jacket 125, and/or an outer jacket 105. The lead stock may be cutto a specific length corresponding to a particular cardiac therapy use,resulting in a lead body (e.g., lead body 300).

An opening 308 may then be formed in the core jacket and/or outer jacket305 of the lead body 300 (operation 1004), such as by cutting or othermeans, and a selected cable conductor 385 of the lead body 300 may beinterrupted (operation 1006) by way of cutting or other methods ofseparating the selected cable conductor 385 into a proximal portion 388and a distal portion 389. Thereafter, a crimp connector 392 (e.g., thecylindrical crimp connector 600 of FIGS. 6A and 6B, or the crimp-throughcrimp connector 700 of FIGS. 7A-7D) or another type of connector may beconnected to the proximal portion 388 of the interrupted cable conductor385 at the opening 308 (operation 1008). A conductive element (e.g., oneof the electrodes 902, 904, 906, or 908 of FIG. 9) may then be coupledto the connector (operation 1010), such as by welding, crimping,swaging, bonding, and the like.

To enhance electrical isolation of the proximal portion 388 of theinterrupted cable conductor 385, at least a segment of the distalportion 389 of the interrupted cable 385, and possibly the entire distalportion 389, may be removed from the lead body 300 (operation 1012),such as by pulling or sliding the distal portion 389 from the firstopening 308, a second opening 309, or the distal end 302 of the leadbody 300. Thereafter, the core jacket and/or outer jacket 305 may bereflowed to fill a void in the lead body 300 created by the removal of asegment or entirety of the distal portion 389 of the interrupted cableconductor 385 (operation 1014). In another example, an insulatingmaterial may be employed to fill such a void (operation 1014). In someexamples, operations 1004 through 1014 may be repeated for multiplecable conductors in the lead body 300, resulting in the lead 900illustrated in FIG. 9.

While the operations 1002 through 1014 are shown as being performed in aparticular order, other orders of performance for the operations 1002through 1014 are also possible. For example, the connecting of theconductive element (operation 1010) may occur after the removal of thedistal portion 389 of the interrupted cable conductor 385 (operation1012) and the reflowing and/or filling operation (operation 1014). Otherorders of performance of the operations 1002 through 1014 may also bepossible.

Those skilled in the art will understand and appreciate that variousmodifications not explicitly described above may be made to the presentdisclosure and still remain within the scope of the present invention.

The resulting lead embodiments disclosed herein may be advantageous forseveral reasons. For example, the interrupting of a selected cableconductor may promote isolation of the selected cable conductors fromother cable conductors in the lead. This isolation may be enhanced bythe removal of a segment, or possibly the entirety, of the distalportion of the interrupted cable conductor. The possible reflowing ofthe core jacket and/or outer jacket of the lead, or the explicit fillingof the lumens associated with the removed portion of the cable conductorusing an insulating material, may further promote the electricalisolation between cable conductors. Additionally, the selective removalof segments or entire distal portions of interrupted cable conductors inthe lead may facilitate enhanced flexibility in areas of the lead atwhich the cable conductors have been removed. Further, by selectivelychoosing particular areas of the lead for cable conductor removal,several different levels of flexibility along specific areas of the leadmay be achieved.

Although the present invention has been described with reference topreferred embodiments, persons skilled in the art will recognize thatchanges may be made in form and detail without departing from the scopeof the invention.

What is claimed is:
 1. A method for manufacturing an implantable cardiacelectrotherapy lead, the method comprising: receiving a length of leadstock, the length of lead stock comprising: a plurality of cableconductors; and an insulating jacket defining at least one lumenextending from a proximal end to a distal end of the length of the leadstock, the plurality of cable conductors located within the at least onelumen; forming an opening in the jacket at an intermediate locationbetween the proximal end and the distal end of the length of lead stock;interrupting at least one of the cable conductors at the opening in thejacket to form a proximal portion and a distal portion of the at leastone of the cable conductors; connecting a crimp connector to theproximal portion of the at least one of the cable conductors at theopening; connecting a conductive element to the crimp connector, whereinthe conductive element is configured to administer an electrotherapysignal transmitted to the conductive element via the proximal portion ofthe at least one of the cable conductors; and removing at least asegment of the distal portion of the at least one of the cableconductors from the at least one lumen.
 2. The method of claim 1,wherein the removing of the segment of the distal portion of the atleast one of the cable conductors from the at least one lumen comprisesremoving an entirety of the distal portion of the at least one of thecable conductors from the at least one lumen.
 3. The method of claim 2,wherein the removing of the entirety of the distal portion of the atleast one of the cable conductors from the at least one lumen comprisessliding the distal portion of the at least one of the cable conductorsfrom the at least one lumen from the distal end of the jacket.
 4. Themethod of claim 1, wherein: the opening comprises a first opening in thejacket; the intermediate location comprises a first intermediatelocation between the proximal end and the distal end of the length oflead stock; and the removing of the segment of the distal portion of theat least one of the cable conductors from the at least one lumencomprises: forming a second opening in the jacket at a secondintermediate location between the first intermediate location and thedistal end of the length of lead stock; interrupting the at least one ofthe cable conductors at the second opening; and sliding a proximalsegment of the distal portion of the at least one of the cableconductors from the at least one lumen via one of the first opening andthe second opening.
 5. The method of claim 1, wherein: the openingcomprises a first opening in the jacket; the intermediate locationcomprises a first intermediate location between the proximal end and thedistal end of the length of lead stock; and the removing of the segmentof the distal portion of the at least one of the cable conductors fromthe at least one lumen comprises: forming a second opening in the jacketat a second intermediate location between the first intermediatelocation and the distal end of the length of lead stock; interruptingthe at least one of the cable conductors at the second opening; andsliding a distal segment of the distal portion of the at least one ofthe cable conductors from the at least one lumen via one of the secondopening and the distal end of the length of lead stock.
 6. The method ofclaim 1, further comprising: filling, with insulating material, at leasta portion of a void remaining in the at least one lumen resulting fromthe removing of the segment of the distal portion of the at least one ofthe cable conductors.
 7. The method of claim 1, further comprising:reflowing the jacket to fill at least a portion of a void remaining inthe at least one lumen resulting from the removing of the segment of thedistal portion of the at least one of the cable conductors.
 8. Themethod of claim 1, wherein: the opening in the jacket defines a proximalend and a distal end along the jacket; and the interrupting of the leastone of the cable conductors comprises cutting the at least one of thecable conductors at the distal end of the opening.
 9. The method ofclaim 1, the connecting of the crimp connector to the proximal portionof the at least one of the cable conductors at the opening comprising:stripping a portion of insulation covering the proximal portion of theat least one of the cable conductors; sliding the crimp connector over adistal end of the proximal portion of the at least one of the cableconductors, the crimp connector comprising a cylindrical crimp tube; andcrimping the crimp connector onto the proximal portion of the at leastone of the cable conductors.
 10. The method of claim 1, the connectingof the crimp connector to the proximal portion of the at least one ofthe cable conductors at the opening comprising: sliding the crimpconnector over a distal end of the proximal portion of the at least oneof the cable conductors, the crimp connector comprising a crimp-throughcrimp tube; and crimping the crimp connector onto the proximal portionof the at least one of the cable conductors to cause the crimp connectorto penetrate insulation covering the proximal portion of the at leastone of the cable conductors to couple electrically the crimp connectorwith the proximal portion of the at least one of the cable conductors.11. The method of claim 1, wherein the connecting of the conductiveelement to the crimp connector comprises one of: welding the conductingelement to the crimp connector; swaging the conducting element to thecrimp connector; crimping the conducting element to the crimp connector;and bonding the conducting element to the crimp connector.
 12. A methodof manufacturing an implantable cardiac electrotherapy lead, the methodcomprising: receiving a length of lead stock, the lead stock comprising:a plurality of cable conductors; and an insulating jacket defining, foreach of the cable conductors, a lumen extending from a proximal end to adistal end of the length of the lead stock, each of the cable conductorsextending along the jacket within its corresponding lumen, the cableconductors being helically wound about central axis oriented along thelength of the lead stock; cutting an opening in the jacket over aselected one of the cable conductors at an intermediate location betweenthe proximal end and the distal end of the length of lead stock;interrupting the selected cable conductor at the opening in the jacketto form a proximal portion and a distal portion of the selected cableconductor; crimping a crimp connector to the proximal portion of theselected cable conductor at the opening; connecting a conductive elementto the crimp connector, wherein the conductive element is configured toadminister an electrotherapy signal transmitted to the conductiveelement via the proximal portion of the selected cable conductor;sliding an entirety of the distal portion of the selected cableconductor from the lumen corresponding to the selected cable conductorfrom the distal end of the length of lead stock; and performing one of:filling, with insulating material, at least a portion of a voidremaining in the lumen corresponding to the selected cable conductor;and reflowing the jacket to fill at least a portion of the voidremaining in the lumen corresponding to the selected cable conductor.